Hi ,
The documents you need are bellow.Your spouse to be has not been living in the UK for 10 years you said,so I would advise you/him to contact UK embassy and ask what additional documents he would have to forward to British Emabassy.

"If you wish to settle in the UK as the spouse or partner of somebody who is permanently and legally resident in the UK, you will be required to make an application in person, and will normally require a second, longer, interview. You should allow three weeks for this second interview. We will need to see the original copies of the following documents. Please bring copies of all originals that you wish to be returned.

a) Signed printout of your completed online application form. Please note that we require one form per applicant. Children need their own form, even when they are included in a parent's passport. Parents may sign the forms of children aged under 16.

b) Your valid passport, Original

d) One recent colour photograph (45 x 35 mm, full-face, taken against a light background)

e) your marriage certificate; Original plus copy

f) evidence of funds available, 3 months of recent bank statements both for you and your spouse; Originals plus copies

g) a written invitation from your UK spouse and his/her passport, including his/her residence permit if he/she is not a British citizen, Originals plus copies

h) evidence of your proposed accommodation in the U.K. (e.g. mortgage or rent agreement) Original plus copy

i) evidence of your spouse's employment or prospective employment in the U.K. (to include salary details) Original plus copy


k) the visa fee (see Visa Fees). Please note that the fees are processing fees. They are not therefore refundable, irrespective of the outcome of your application. Please also note that fees are payable for children who are accompanying a parent on the parent's passport."

 

Can I join my husband, wife, civil partner, fiancé, fiancée or proposed civil partner in the UK?
You can apply to join your husband, wife, civil partner, fiancé, fiancée or proposed civil partner in the UK as long as:

they currently live and are settled in the UK, or
they are coming to live permanently in the UK.

You will need additional documents as well as healthy bank balance.Ask embassy,because I am not sure about the requirements for the returning UK citizens.